JavaScript encrypts and decrypts the parameters in the url

Today, when working on an old project, I encountered a requirement. I encrypted and decrypted the parameters in the url in JavaScript, and found this useful code from the Internet:

The code copy is as follows:

<SCRIPT LANGUAGE="JavaScript">

<!-- Begin

function Encrypt(str, pwd) {

if(str=="")return "";

str = escape(str);

if(!pwd || pwd==""){ var pwd="1234"; }

pwd = escape(pwd);

if(pwd == null || pwd.length <= 0) {

alert("Please enter a password with which to encrypt the message.");

return null;

}

var prand = "";

for(var I=0; I<pwd.length; I++) {

prand += pwd.charCodeAt(I).toString();

}

var sPos = Math.floor(prand.length / 5);

var mult = parseInt(prand.charAt(sPos) + prand.charAt(sPos*2) + prand.charAt(sPos*3) + prand.charAt(sPos*4) + prand.charAt(sPos*5));

var incr = Math.ceil(pwd.length / 2);

var modul = Math.pow(2, 31) - 1;

if(mult < 2) {

alert("Algorithm cannot find a suitable hash. Please choose a different password. /nPossible considerations are to choose a more complex or longer password.");

return null;

}

var salt = Math.round(Math.random() * 100000000) % 100000000;

prand += salt;

while(prand.length > 10) {

prand = (parseInt(prand.substring(0, 10)) + parseInt(prand.substring(10, prand.length))).toString();

}

prand = (mult * prand + incr) % modul;

var enc_chr = "";

var enc_str = "";

for(var I=0; I<str.length; I++) {

enc_chr = parseInt(str.charCodeAt(I) ^ Math.floor((prand/modul) * 255));

if(enc_chr < 16) {

enc_str += "0" + enc_chr.toString(16);

}else

enc_str += enc_chr.toString(16);

prand = (mult * prand + incr) % modul;

}

salt = salt.toString(16);

while(salt.length < 8)salt = "0" + salt;

enc_str += salt;

return enc_str;

}

function Decrypt(str, pwd) {

if(str=="")return "";

if(!pwd || pwd==""){ var pwd="1234"; }

pwd = escape(pwd);

if(str == null || str.length < 8) {

alert("A salt value could not be extracted from the encrypted message because it's length is too short. The message cannot be decrypted.");

return;

}

if(pwd == null || pwd.length <= 0) {

alert("Please enter a password with which to decrypt the message.");

return;

}

var prand = "";

for(var I=0; I<pwd.length; I++) {

prand += pwd.charCodeAt(I).toString();

}

var sPos = Math.floor(prand.length / 5);

var mult = parseInt(prand.charAt(sPos) + prand.charAt(sPos*2) + prand.charAt(sPos*3) + prand.charAt(sPos*4) + prand.charAt(sPos*5));

var incr = Math.round(pwd.length / 2);

var modul = Math.pow(2, 31) - 1;

var salt = parseInt(str.substring(str.length - 8, str.length), 16);

str = str.substring(0, str.length - 8);

prand += salt;

while(prand.length > 10) {

prand = (parseInt(prand.substring(0, 10)) + parseInt(prand.substring(10, prand.length))).toString();

}

prand = (mult * prand + incr) % modul;

var enc_chr = "";

var enc_str = "";

for(var I=0; I<str.length; I+=2) {

enc_chr = parseInt(parseInt(str.substring(I, I+2), 16) ^ Math.floor((prand/modul) * 255));

enc_str += String.fromCharCode(enc_chr);

prand = (mult * prand + incr) % modul;

}

return unescape(enc_str);

}

// End -->

</script>

In the future, if you encounter encryption and decryption problems, you can write the above code directly into a js file and then do it. It's easy to save trouble. . . .